Voltage transformer with removable high voltage fuses

ABSTRACT

A high voltage transformer has a fuse with high cutoff power which can be directly extracted so that all measurements from the transformer can be carried out without shutting off voltage.

United States Patent Robert Conroi 32, rue Ste Catherine, 51 Ste Menehould, Marne, France [72] Inventor [21] Appl. No. 767,383

[22] Filed Oct. 14, I968 [45] Patented June 29, 1971 [32] Priority Oct. 19, 1967 [33] France [54] VOLTAGE TRANSFORMER WITH REMOVABLE HIGH VOLTAGE FUSES 4 Claims, 6 Drawing Figs.

[52] 11.8. C1 317/15, 337/194 [51] Int. Cl H02h 7/04 [50] Field of Search 337/194. 168:317/14, [5;336/105 [56] References Cited UNITED STATES PATENTS 3,007,125 10/1961 Farbee 336/221 FOREIGN PATENTS 829,312 3/1960 Great Britain 317/15 Primary Examiner-William M. Shoop, Jr. Assistant Examiner-Harry E. Moose, Jr. Attorney-Burns, Lobato & Zelnick ABSTRACT: A high voltage transformer has a fuse with high cutoff power which can be directly extracted so that all measurements from the transformer can be carried out without shutting off voltage.

I PATENTED JUN29 IHYI SHEET 1 OF 3 PATENTED JUN29 um SHEET 2 [IF 3 VOLTAGE TRANSFORMER WITH REMOVABLE I-IIGI-I VOLTAGE FUSES The present invention is concerned with a voltage transformer assembly comprising a high-voltage fuse with high shutoff power which can be insulated from the high-voltage network without additional means and is intended to serve as a power transformer or as a voltage measuring transformer.

This transformer can be designed for primary voltagesof from one thousand to several tens of thousands of volts. The secondary voltages delivered can be of any value. This apparatus can accordingly serve to measure voltages on high or middle voltages by connecting the secondary with a voltmeter, or a wattmeter or to feed devices which require a power of several thousands of watts.

Voltage transformers with fuses incorporated therein are known. They have for their purpose to avoid, in case of a flaw, the explosion of the transformer which might cause serious damage in the prefabricated high-voltage cell or in the transformer station where the apparatus is located.

In all the devices presently known, these transformers must always be associated with a shutoff. device which makes it possible to insulate them from the network on which they are connected.

These cutoff devices are heavy and costly.

The invention thus is concerned with a power or measuring voltage transformer with dry insulation which has the following characteristics:

a. protection ensured by high-voltage fuses with high cutoff power.

b. insulated from the high-voltage lines without any additional apparatus.

c. no-return device for the low-voltage circuit.

d. interchangeability of the transformer without access to the high-voltage lines.

This apparatus is characterized by the fact that-its fuse 3 with high shutoff power can be extracted directly by means of an original arrangement which makes it possible to carry out all measurements on the transformer without shutting off voltage ofa set of bars or on the network. 7

The simple fact of removing the fuse automatically shuts off the low-voltage circuit thus making impossibleany return voltage.

This transformer can be made as a voltage transformer or with a single insulated pole, with two insulated poles, with three insulated poles, without changing the principle thereof,

for all the conventional or special ratios of a thousand volts to several tens of thousands of volts.

The invention will be more fully understood from the following description in conjunction with the accompanying drawings which illustrate by way of example two preferred embodiments of the invention. In the drawings:

FIG. 1 is a side view partially in section of a transformer and fuse assembly in accordance with the invention.

FIG. 2 is a cross section taken on the line 2-2 in'FIG. 1.

FIG. 3 is a partial section taken on the line 3-3 in FIG. 1.

FIG. 4 is a partial end view taken from the right in FIG. 1 with the fuse removed.

FIG. 5 is an end view from the left in FIG. 1 with a portion shown in cross section, and

FIG. 6 is a view similar to FIG. 1 showing a modification.

In the embodiment of FIG. 1, there is shown a voltage transformer with insulated pole.

In this embodiment, this voltage transformer is protected by a high-voltage fuse which is directly removable under voltage.

The transformer and fuse assembly is constituted by the three following elements:

the removable and movable transformer,

the container holder secured on the metallic wall of a highvoltage cell,

the fuse container which is removable under voltage.

The movable and removable transformer unit 26 comprises a core of magnetic sheets 18 of rectangular shape with one side resting on base 27 and the other supporting the windings. These comprise, starting from the core towards the exterior, a frame 19 carrying a low-voltage winding 20 separated from the high-voltage winding 22 by an insulated tube 21. The transformer windings and core are enclosed in a synthetic resin casing having a cylindrical nose portion.

One of the ends of the low-voltage winding 20 issues at terminal 29 while the other extremity issues at terminal 31 after passing through a low-voltage fuse the fuse holder of which is mechanically integral with the removable container 8 to permit shutting off simultaneously the high-voltage feed and the low-voltage circuit when the container 8 is removed.

The high-voltage winding 22 has an extremity 30 which is connected to the ground. The other extremity fed with high voltage is connected to a sleeve 17 positioned at the extremity of a cylindrical portion which forms the nose of the transformer casing.

The container holder 1, also of synthetic resin is secured by several bolts on the metallic wall 4 of a high-voltage cell according to FIGS. 1 and 5. This securing can be fluidtight in the case where the high tension bars are immersed in oil. There is thus obtained a fluidtight connection of the voltage terminals.

. A drop bolt 14 ensures the fluidtightness of the front part of the container holder.

The container holder 1 comprises at its lower part a lower cylinder in the bottom of which is located a plug 16 connected by a copper connection to a ring 7. The latter is located in the upper cylinder intended to receive the removable container 8 'and constitutes the upper part of the container holder.

On the latter is secured a lock plate 23 and a locking device 24 shown in its lower position on FIG. 1. In high position, only possible when the container 8 is removed, the stud of locking means 24 can penetrate in the upper cylinder preventing the reinsertion of the container.

The removable container 8 also made of synthetic resin has the shape of a cylinder closed at one end by a cover 10 secured by screws 9 equipped with a handle 11. It slides in two groove as shown in FIG. 4. It extends as a half cylinder containing fuse 3 and terminates by a metallic ring 2 which is screwed on.

FIGS. 2, 3 and 4 show different cross sections of the container and the container holder and of the high-voltage fuse 3.

Fuse 3 is positioned between the high-voltage line and the beginning of the high-voltage wiring 22 and is removable. It is provided at its rear part with two flexible supports 5 equipped with a silver stud 6 ensuring contact with ring 7,as shown in FIG. 3. The front part of fuse 3 terminates in a sleeve 12 which fits a plug 13 integral with the fluidtight drop bolt 14, connected to the set of high-voltage bars. Sleeve 12 is centered relative to ring 2 by a jaw 15 according to FIG. 2.

OPERATION a. Set of bars under average voltage in oil.

Fluidtightness is ensured on the metallic wall 4 by the small collar of the container holder. The synthetic resin of the container holder ensures fluidtightness on part 14.

The container 8 is removed and locked out by the stud of part 24 which is in raised position. The lower part of the locking means 24'being then withdrawn in its housing, transformer 26 is fitted in and its nose (FIG. 1) carrying sleeve 17 fits on the plug 16 V in the lower cylinder of the container holder. The locking means 24 are unlocked and fall back into lowered position preventing removal of transformer 26. The stud of locking means 24 which lowers in the wall of the container holder and makes it possible thus to insert the fuse 3 by pushing on the handle 11 until cover 10 of container 8 conlows:

'17 and plug 16 since the end of the highvoltage winding is connected directly to the ring 7. v

The threaded outer extremity of part 14 is then removed by a plug in such a way that the monolithic assembly obtained be removable from the network by pulling on handle 25 but after having removedthe fuse holding container 8.

According to another modification shown in FIG. 6 the removable movable transformer 126 has in its rear part a lock 137 permanently secured by construction. It immobilizes in connected position the transformer 126 on container holder 101.

The container holder 101 comprises in its rear part a permanent lock 134. This lock uses the same key 135 as lock 137. This key 135 can only be turned if the container 108, is in a well-defined geometric position. The part 136 is integral with container holder 10].

Removable container 108 has on its rear part a metallic flange 110 equipped with a handle 111. On this flange are located contacts which close the secondary circuit 120 of the transformer when the container 108 is closed position in accordance with the drawing. i

To remove transformer 126 it is necessary to proceed as fol- 1. Remove completely container 108 by pulling on handle 111 in such a way that ring 102 contacts part 136.

2. Remove the high cutoff fuse 103. v

3. Replace fuse 103 by a metallic rod the front extremity of which lodges in the jaws 115 of the container and the other extremity engages in the lock 134, thus positioning container 108 inside container holder 101 in such a way that blade 132 on ring 102 contacts ring 107.

Under these conditions parts 102-1 -132-107-1 16 and l 17 are electrically connected to the ground by parts 1 9:13? an it is only then that it is possible to remove key 135 from lock 134.

4. Key 135 goesin lock 137 and the transformer 126 is then freed by unlocking lock 137 from piece 136. Transformer 126 .is then removed by pulling to the rear.

The above assembly repeated strictly in the same order but in the opposite way are necessary in order to place the assembly again under voltage.

The present assembly makes it possible to replace the transformer without shutting off voltage on the network.

What I claim is:

1. A transformer assembly comprising an elongated insulated container including an upper cylinder and a lower cylinder, each of said cylinders having a closed end and an open end; a contact ring recessed peripherally in said upper cylinder intermediate its ends; a metallic ring within said upper cylinder at said closed end thereof; an insulated fuse holder slidably mounted in said upper cylinder and including a semicircular fuse holding portion secured to said metallic ring and a cylindrical portion closed by a cover abutting the open end of said upper cylinder; a fuse in said fuse holding portion connected to a high-voltage source and with said contact ring; an electrical contact at the closed end of said lower cylinder, a transformer comprising an insulated casing having a nose portion slidably received in said lower cylinder, windings enclosed in said casing including a high-voltage winding and a low-voltage winding and a contact on said nose portion connected with said high-voltage winding and engageable with said contact of said lower cylinder to connect said high-voltage winding through said fuse to said high-voltage source when both said fuse holder and said transformer are in place in said container holder, said high-voltage winding having a grounded extremity and another extremity connected to said high-voltage source; said high-voltage winding having an extremity connected to said fuse through said contact ring; and means for locking said fuse holder and transformer on said container to prevent removal or insertion of said transformer when said fuse holder is in place in said container holder.

2. A transformer assembly according to claim 1, wherein said locking means is located between one end of said transformer and said open'end of said upper cylinder and comprising a part movable from a first position in which it prevents disassembly of said transformer from said container but allows introduction or removal of said fuse holder in said upper cylinder.t'o a second position in which it enters said upper cylinder to permit removal of said transformer from said container but prevents insertion of said fuse holder.

3. A transformer assembly according to claim 2, wherein said locking means comprises a first lock for locking said transformer on said container and a second lock for locking said fuse holder onto said container, said locks being operated by a key normally in said second lock and removable therefrom to open said first lock only when said fuse holder and said transformer are grounded to permit removal of said transformer from said assembly.

4. A transformer assembly according to claim 3, comprising means for positioning said fuse holder in a partially withdrawn position in which said key is removable from said second lock. 

1. A transformer assembly comprising an elongated insulated container including an upper cylinder and a lower cylinder, each of said cylinders having a closed end and an open end; a contact ring recessed peripherally in said upper cylinder intermediate its ends; a metallic ring within said upper cylinder at said closed end thereof; an insulated fuse holder slidably mounted in said upper cylinder and including a semicircular fuse holding portion secured to said metallic ring and a cylindrical portion closed by a cover abutting the open end of said upper cylinder; a fuse in said fuse holding portion connected to a high-voltage source and with said contact ring; an electrical contact at the closed end of said lower cylinder, a transformer comprising an insulated casing having a nose portion slidably received in said lower cylinder, windings enclosed in said casing including a high-voltage winding and a low-voltage winding and a contact on said nose portion connected with said high-voltage winding and engageable with said contact of said lower cylinder to connect said high-voltage winding through said fuse to said high-voltage source when both said fuse holder and said transformer are in place in said container holder, said high-voltage winding having a grounded extremity and another extremity connected to said high-voltage source; said high-voltage winding having an extremity connected to said fuse through said contact ring; and means for locking said fuse holder and transformer on said container to prevent removal or insertion of said transformer when said fuse holder is in place in said container holder.
 2. A transformer assembly according to claim 1, wherein said locking means is located between one end of said transformer and said open end of said upper cylinder and comprising a part movable from a first position in which it prevents disassembly of said transformer from said container but allows introduction or removal of said fuse holder in said upper cylinder to a second position in which it enters said upper cylinder to permit removal of said transformer from said container but prevents insertion of said fuse holder.
 3. A transformer assembly according to claim 2, wherein said locking means comprises a first lock for locking said transformer on said container and a second lock for locking said fuse holder onto said container, said locks being operated by a key normally in said second lock and removable therefrom to open said first lock only when said fuse holder and said transformer are grounded to permit removal of said transformer from said assembly.
 4. A transformer assembly according to claim 3, comprising means for positioning said fuse holder in a partially withdrawn position in which said key is removable from said second lock. 